Carburetor



Jan- 19 l965 R. l.. CONANT ETAL 366611 CARBURETOR Filed Sept. 6. 1962 J0 "j 4 47 4 l u INVENTORS.

ROBERT L. 00A/ANT. MAX L. MlffLX 3,166,611 CAREURETOR Robert L. Conant, 426 Fairmont Drive and Max L.

McNeely, '76 Valley Drive, both of Decatur, lll.

Filed Sept. 6, 1962, Ser. No..22l,721 l 4' Caizns. (Cl. E61-41) This invention relates to improvements in carburetors, having reference particularly to fuel and air supply for idling. Y

In carburetor practice, it is quite' customary to provide an idling nozzle for supplying fuel to the engine when the throttle valve is closed or nearly closed, or in idling position, at which time the main nozzle is ineffective. ln carburetors ofthis character the vacuum affecting the idling nozzle decreases very rapidly asthe throttle is opened. This reduces the flow of mixture to the idling nozzle and coupled with the excess of airadmitted by the throttle produces a mixture too lean to give satisfactory results. Until `the engine attains a certain speed, equivalent to from six 'to ten miles an hour vehicle speed for certain motor vehicles, the suction isinsutiicent to draw a charge from the main nozzle around which the vacuum is not very great because the ilow of air around the nozzle necessarily is not much restricted., At such' engine speeds, therefore, the engine will fail to run satisfactorily, this phenomenon being called frequently a spot. @ne of the objects of this invention is the provision of means to eliminate such spots. i

Inthe down draft type carburetor there is a barrel portion below the venturi chamber therein'and through which the atomized fuel Vand air flow to 'the intake manifold; the throttle valve is also located there to control the passage of the mixture therethrough.

Along the outside of the barrel, or conduit portion there is a channel for conductingfuel to two openings through nited States i Patent O1 thebarrel wall for passage of the fueltfrom the channelV to the barrel during slow running of the engine. A solid `'adjusting screw is usually provided to control the passage of fuel into the interior of the barrel.

The main object of thisinvention is to provide a special unitary metering screw having an air bleed, which may be used in place of the usual adjusting screw for the slow running control of the engine to further reatomize lthe fuel which is being drawn from the slow ruiming fuel lchannel through the opening controlled by the adjusting screw, producing a good homogeneous mixture and to avoid a patchy wet mixture which causes spots, and

also uneven running and waste of fuel under slow running conditions.

Y Another object of this invention is to provide a unitary metering screw with an air bleed to attain smoother running ofthe vengine under slow running conditions due to havingra `better homogeneous mixture and further prelvent stalling of the engine, which could be very dangerous under present day crowded ,road driving conditions. j, A'further object of this inventionis to provide a'unitary'metering valve screw with an air'bleed to make starting of the engine easier under humid summerand cold winterconditioiis by reason of further atomization of the idling fuel; i

FIGURE 1 is a vertical section taken through the imid# ,'dle'of the nozzle and carbureting chamber and through the iioat bowl;

' slightly open, to control the volume of air and gas which V of said threads 5 9 and when assembled between the head` sassari Patented Jan. 19, 1916157' ice,

FIGURE 2 is an enlarged plan view Vof the idling screw shown in FIG. l; i

FIGURE 3 is a detail end View of the pointed end of the idling screw; i l Y FIGURE 4 is an axial sectional view taken substantially on the line 4 4 of PEG. 2;.andl

FIGURE 5 is a Vfragmentary enlarged sectional view diagrammatically showing the relation of the unitary met ering screw having an air bleed to the idling port in the barrel wall portion of the carburetor shownl in FlG. l.. ,i Similar reference characters refer to like parts throughout the views.

In the drawing, the numeral lil indicates the carburetor proper, while 11 relates to the air horn casting thereof, 12

l joining the air space 26 in the ioat bowl above the fuel 27 therein. VA float 28 is pivoted-on shaft 29 with its arm Sil in contact with rear end of the metering pin 32. AY

secondventuri 33 is arranged in the throat of the venturi 21, such second venturi 33 having a main fuel nozzle 35 arranged therewith, the upper end of the nozzle 35 terminating in venturi 33 while its lower end terminates below the fuel levelrin the float bowl 13, said nozzle 35 having a plurality of fuel passages passing through the ytubular wall and lower end thereof.

In FIGURES l and 5 there is` clearly shown the throttle valve 23 `in substantially closed position, and below and adjacent the upper edge portion of the valve 33 is an idling port, or jet 46, communicating with a slow speed fuel sup'- ply channel 41, there also being provided an auxiliary port 42', located in advance of the jet 40 and adjacent the upper edge'portion of said valve 33. The jet t? is provided with a conical seat 43 at the entrance end of the jet opening which is adjacent the channel 41.*

The unitary metering screw has a shank threaded through a boss 46 of the barrel casting 14 at a location where it will cross the fuel channel 41. The shank is generally cylindrical at its forward end 49 but is provided with a tapered or conical end portion 47 to engage the seat 43 and close the passage or, by reason of its being may pass through the jet opening 49. This metering screw 4S, or slow running adjusting screw, is provided with a head 4S at its end opposite from its.conical end 47,

providing a convenient handle for operating the screw. The rear and central exterior surface portions of said screw 45 are provided with threads S- for engagement with the internal threads in boss 46. n

A spring 51 is axially sleeved about the rear portion es of the screw and the boss de of the casting, it provides sucient tension on the screw threads so that the adjusting screw will maintain the position to which' it is adjusted. The outer suriace of the screwed, with the exception of headl 48, is provided with a longitudinally extending groove 55 of V-shaped configuration, the base of ,the groove'56 in said forward vendl 49 beingat leastone thirty-second .of ,an inch below the top surface thereof and parallel therewith. The groove extending through the threads 5? is therefore deeper and of greater crosssectional area in the threaded area. The groove extends to the extreme end of the conical end d'7, and as seen in FIG. 4, the depth of the V-slot decreases as it approaches the apex of the conical end 47; The groove 55 will convey air from the exterior of the arburetor barrel directly to the jet opening 40.

From the foregoing description it can be seen that an improved metering screw 45 is provided for controlling the flow of air and gasoline to and from the jet opening The head 4S is provided with a transverse milled slot whereby the end of the blade of a screw-driver can be inserted for turning the screw 45; the screw-driver cannot block the entrance of air to the tl-shaped groove and prevent the free flow of air. Thus, adjustment is effected either manually or by a screw-driver while the rigid assembly is functioning in its normal manner. The V-shaped groove 55 being in the exterior surface of the screw 45 is normally clean, and readily cleaned if the occasion arises. Y By the prior art it is common to use internal air bleed passages, these passages being so small that they become clogged with dirt and fail to function, and cannot be cleaned without damage thereto by enlargement thereof by using a drill or a piece of wire. Applicant can clean the tf-shaped groove with a small brush or liquid cleaner if the occasion should arrive. As noted, the coil spring 51 is constructed of wire very small in cross-section and has a large number of coils, the coils forming a protector and an air filter for the tl-shaped passage, screening the air about the screw 55 preventing any dirt from clogging the V-shaped groove.

The improved metering screw 4S provides auxiliary' air in such a manner that it improves economy by reducing the flow of rich liquid idling fuel, when the engine is acting as a brake, or decelcrating. That is, when the throttle is substantially closed, and the motorie decelerating, the engine manifold suction on the jet port 40 is increased, and fuel drawn into the engine is wasted. During such times the V-shaped groove 55' acts to lessen the quality of fuel drawn into the engine and thereby provides economy.

The opening between the conical seat 43 and the conical end portion 47 of the screw 45 can be less than the opening thereof with the conventional type screw; that is the space can be approximately .009 as'compared to the conventional requirement of point .018 across. This condition is due to the V-shaped groove 55 which is approximately .0312 deep on an average.

Owing to the fact that the V-shaped groove is on the exterior of the screw and extends to the apex thereof, the lighter mixture of air by-passes the space or conduit between the conical surface of the screw and the conical seating 43 and passes through the jet opening, or port and insuring a homogeneous mixture. This condition effects the metering screw to have a relatively closer position to its conical seat which gives an increased area ratio in relation to the same axial movement of the metering screw. By this construction and assembly, the engine, at low speed condition is much more sensitive and responds more quickly for a given movement of the metering screw 45, all time lapse between the movement of the screw and engine response being removed. Therefore, this invention provides an adjusting screw which is easier to operate and produces a new and improved metering screw, the metering screw playing a very important part regarding performance and fuel consumption.

Therefore, when the engine to which the carburetor Y"is attached is idling, fuel passes from the float chamber through the calibrated bore in the bottom of the fuel nozzle 35, through opening in its side walls'y into chamber 66 and supply channel 41 and through ports 42 and '43. The fuel is drawn from a point beneath the normal level of fuel in the float bowl and free of air. The delivery of fuel to chamber et) and its mixture with air at that point is, of course, dependent upon the engine demand through port 43 alone or in conjunction with 42, as the position of the throttle 23 over the latter may permit. As the throttle is opened slightly, port 42 as shown is also immediately or progressively uncovered, whereupon a large quantity of mixture is-led to the manifold of the engine, preventing spotsj It is clearly shown that fuel for the main nozzle is delivered by fuel nozzle 35 into venturi 33; then air and fuel mixture enters the throat 20, passing downwardly past the throttle valve 23 as it is opened. Air and fuel pass together into the manifold of the engine in a ne vapor mixture, and the amount thereof is in accordance to the opening of the throttle valve 23.

It is clear that Abetter engine performance is obtained with applicants device with respect to acceleration than by using the regulation type idle mixture screws. Better mixtures are obtained since over rich mixtures are elim-v inated from syphoning from the high speed jet. In other words there is no lag, or spots between idle and acceleration commonally noticed in standard cars. Pick-up of speed is instantaneous without lag.

In a few words, therefore, certain important features of this invention consists in the use of two venturies with a single fuel nozzle and, in conjunction with an auxiliary chamber, supply channel and jet port regulated by an improved and novel mete 'ng screw embodying a V- shaped groove upon the exterior thereof.

While we have described more or less in detail a specific embodiment of our invention, it is to be understood that the foregoing showing and describing the structure are for illustration only, and for the purpose of making the disclosure of the invention thoroughly clear and understanding or understandable to those interested in the same. We vdesire that minor changes in details of construction, proportions and arrangement of parts may be resorted to, when required, without sacrificing any of the advantages of our invention as set forth.

We claim:

1. In a carburetor of the downdraft type, an air horn at the upper end thereof having a conduit therethrough with a choke valve therein, a venturi casing below said air horn having a venturi extending therethrough and with a fuel nozzle therein, a barrel casting below said venturi casting having a conduit-therethrough and having a throttle valve therein to control the passage of gasses Vthrough said conduit, a slow running fuel channel with a wall between it and the conduit of said barrel casting, said wall having an opening therethrough extending from the slow running fuel channel to said conduit adapted for conveying gases therein formed from atmospheric air and fuel, a threaded aperture extending horizontally through the external wall of said barrel casting for supporting an adjusting screw, a solid adjusting screw having a threaded shank assembled in said threaded aperture, said screw having a conical end portion adjacent but spaced from the bore of said opening in said wall adjacent said conduit, said screw having a needle portion between said threaded shank and said conical end portion and of a diameter less than that of said threaded shank, said screw serving toV control the opening in said wall, and said adjusting screw having a continuous V -shaped groove along its exterior longitudinal surface and extending to the apex of said conical end portion thereby communicating with the atmosphere outside said barrel casting and said slow running fuel channel forming gasses therein of a mixture of fuel and air at a location in said channel upstream from the portion of the opening controlled by the screw, and said V-shaped groove of said conical end portion communicating between said slow running fuel channel and said conduit, bypassing some of the gasses from said `fuel channel to said conduit in said barrel casting.

2. In a carburetor of the downdraft type, a barrel having a throat extending therethrough, said barrel having an exterior housing wall, a throttle valve in said throat to control the passage of gasses throught said throat, a slow speed fuel supply channel with a substantially vertical wall between it and the said throat having a port opening with a conical seat extending therethrough from the said supply channel to said throat, a solid adjusting `screw embodying a threaded shank portion, a needle portion and with a conical end portion at one end of said needle portion, said conical portion adjacent but spaced from the conical seat of said port opening and said adjusting screw having a single continuous V-shaped groove arranged in the longitudinal exterior surface of its threaded shank, the needle and conicial portions, said V-shaped groove extending substantially the entire length of said shank portion, said needle portion and to theapex of the said conical end portion, the depth of the V-shaped groove of said conical portion decreasing as it approaches the apex of the conical portion, the depth of the V-shaped groove in the threaded shank portion and said needle portion being the same throughout the entire length thereof, a threaded bore in the exterior wall of said carburetor for supporting said adjusting screw horizontally relative to the vert-ical axis of said throat, the threaded shank portion having external threads thereon and extending through said threaded bore in said exterior Wall 0f said barrel, the proximal end of said V-shaped groove being in communication with the atmosphere, the distal end of said V-shaped groove being in communication with the 10W speed fuel supply channel allowing atmospheric air to pass in the channel and form gases consisting of a mixture of fuel and air at a location in said channel upstream of the portion of the conical seat in said port opening controlled by the said screw and said V-shaped groove in said conical end portion bypassing some ofthe gasses in said channel to the said throat.

3. A carburetor as in claim 2 wherein said V-shaped groove in said shank portion of said screw is located at a distance above the conical seat when said screw is arranged in a position with the groove at the .top thereof.

4. An air bleed idling valve according to claim 3 wherein the vertex of said V-shaped groove in said shank member is at a distance of at least .036 inch inwardly from the root circumference of the .threads on the threaded v portion of said shank member.

References Cited in the tile of this patent UNITED STATES PATENTS 

1. IN A CARBURETOR OF THE DOWNDRAFT TYPE, AN AIR HORN AT THE UPPER END THEREOF HAVING A CONDUIT THERETHROUGH WITH A CHOKE VALVE THEREIN, A VENTURI CASING BELOW SAID AIR HORN HAVING A VENTURI EXTENDING THERETHROUGH AND WITH A FUEL NOZZLE THEREIN, A BARREL CASTING BELOW SAID VENTURY CASTING HAVING A CONDUIT THERETHROUGH AND HAVING A THROTTLE VALVE THEREIN TO CONTROL THE PASSAGE OF GASES THROUGH SAID CONDUIT, A SLOW RUNNING FUEL CHANNEL WITH A WALL BETWEEN IT AND THE CONDUIT OF SAI D BARREL CASTING, WALL BETWEEN IT AND THE CONDUIT OF SAID BARREL CASTING, SAID WALL HAVING AN OPENING THERETHROUGH EXTENDING FROM THE SLOW RUNNING FUEL CHANNEL TO SAID CONDUIT ADAPTED FOR CONVEYING GASES THEREIN FORMED FROM ATMOSPHERIC AIR AND FUEL, A THREADED APERTURE EXTENDING HORIZONTALLY THROUGH THE EXTERNAL WALL OF SAID BARREL CASTING FOR SUPPORTING AN ADJUSTING SCREW, A SOLID ADJUSTING SCREW HAVING A THREADED SHANK ASSEMBLED IN SAID THREADED APERTURE, SAID SCREW HAVING A CONICAL END PORTION ADJACENT BUT SPACED FROM THE BORE OF SAID OPENING IN SAID WALL ADJACENT SAID CONDUIT, SAID SCREW HAVING A NEEDLE PORTION BETWEEN SAID THREADED SHANK AND SAID CONICAL END PORTION AND OF A DIAMETER LESS THAN THAT OF SAID THREADED SHANK, SAID SCREW SERVING TO CONTROL THE OPENING IN SAID WALL, AND SAID ADJUSTING 